West Nile virus (WNV) is a flavivirus commonly found in Africa, West Asia, and the Middle East. The virus was introduced into the United States in 1999. Case-fatality rates during the 1999-2000 U.S. epidemics ranged from 3 percent to 15 percent and were highest in the elderly. The virus is expected to over-winter during 2000-2001 and re-emerge in the Northeast over a wider area. The goal of this project is to develop epitope reagents that could be used in a diagnostic test (such as a tetramer assay) for cell-mediated response to WNV. These reagents may be useful for screening exposed individuals, for investigating the immunopathogenesis of WNV disease in humans, as a component of the surveillance effort and/or, eventually, as a tool for measuring WNV vaccine-related immune responses. The specific aims of this project are to: Select WNV "unique" sequences for potential immunogenicity, using EpiVax tools Confirm MHC binding of selected ligands in T2 MHC binding assays Confirm T cell response to the WNV epitopes by ELIspot assay Begin the process of constructing several tetramers containing WNV epitopes with the NIH tetramer contract service. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE